Conventionally, a bottle is filled by using hot filling, where the bottle is filled with a content liquid, such as a beverage, at a high temperature for sterilization. A synthetic resin blow molded bottle, which may be filled using hot filling, is generally provided, in a trunk or a shoulder thereof, with reduced pressure absorbing panel portions to absorb (mitigate) reduced pressure that is generated inside the bottle when the content liquid is cooled after being filled at the high temperature (refer, for example, to Patent Literature 1). By the reduced pressure absorbing panel portions being deformed to absorb the reduced pressure generated inside the bottle, unsightly deformation and poor appearance of the bottle are prevented.